Teach mandoc about IEEE Std 1003.1-2008, 2017 Edition ("POSIX.1")

[0mp]

Summary

Teach mandoc about IEEE Std 1003.1-2008, 2017 Edition ("POSIX.1")

There is a macro in the mdoc(7) language to specify various standards in manual
pages. For example:

    .St -p1003.2

would render as

    IEEE Std 1003.2 ("POSIX.2")

Unfortunately, mandoc upstream has not added an appropriate abbreviation for
IEEE Std 1003.1-2008, 2017 Edition ("POSIX.1").

This commit adds this abbreviation so that we can use it in our manual pages.

[0mp]

A similar revision from the past: D13349

[bapt]

have you upstreamed that first?

[0mp]

In D23944#526235, @bapt wrote:

have you upstreamed that first?

No, not yet.

[bapt]

this should be upstreamed first then committed to the source tree as validated upstream.
I will probably in this case just update the snapshot of mandoc we are using.

[0mp]

In D23944#526283, @bapt wrote:

this should be upstreamed first then committed to the source tree as validated upstream.
I will probably in this case just update the snapshot of mandoc we are using.

OK! Let's do it this way.